can anyone identify

This tank just came my way via a friend who picked it up to solve my bike's needs. Unfortunately it won't exactly work for me. I don't know the year/make of the bike it's for...Hence this post. Any ideas? I've been chasing tanks for my bike ('81 yamaha xj550 maxim) and all the tanks look...

Hi guys after a re torque the leaks have persisted and as she is a little noisy for about 5/10 seconds until the bike warms up that seems from the info on the forum to indicate possibly a flopping cam guide I drained the sum in preparation for a engine strip to replace the gaskets and have a...